Chromaticity Control in Light‐Emitting Electrochemical Cells via Thermally Activated Emission in Assemblies of a BN‐Doped Pyrenyl Hydrocarbon

This work outlines the synthesis and photo‐/electro‐luminescent behavior of a new C‐shaped BN‐doped benzenoid hydrocarbon using N‐directed borylation in a unique lattice‐embedded graphitic C 2 –B–N motif at the pyrene K‐region. This BN‐doped polycyclic aromatic hydrocarbon (PAH) exhibits a green fluorescent emission in solution with a photoluminescent quantum yield of 91%. In contrast, thin‐films applied to light‐emitting electrochemical cells (LECs) feature a temperature‐dependent dual‐emission, including a broad yellowish band and a well‐structured near‐infrared band that are barely met in the prior art. What is more striking, this temperature‐dependent dual‐emission can be easily controlled in LECs with the driving conditions, realizing green‐yellow ( x/y CIE color coordinates of 0.36/0.61; stabilities of 200 h; efficiency of 0.30 lm W −1 ) and yellow‐orange ( x/y CIE color coordinates of 0.50/0.49; stabilities of ≈70 h; efficiency of 0.26 lm W −1 ) devices. Finally, the expected greenish devices ( x/y CIE color coordinates of 0.30/0.62; stabilities of 0.3 h; efficiency of 0.46 lm W −1 ) can be fabricated using a host:guest active layer that disrupts the formation of the thermally activated emissive assemblies. Hence, this work highlights the films' thermally activated emission behavior to control device chromaticity using this BN‐doped PAH.